Tobacco treatment



Patented July 5, 1938 vTQJBAOCO TREATMENT Alfred T. Hawkinson, Palmyra,N. .L, assimi- M E. I. du Pont de Nemours & Company. Wilmington, Del, acorporation of Delaware No Drawing.

Application July 80, 1937. Serial No. 156,563

Giaims. (c 131-55 This invention relates to the treatment of tobacco inorder that its properties may be im proved thereby rendering'it morevaluable. More particularly, the invention relates to the treat- 5 mentof leaf tobacco such as that used in the preparation of cigar wrappersin order that the characteristics of the tobacco leaf may he ran-- deredmore suitable for use in the manufacture of cigars.

It may be said that the invention more especially concerns itself withthe treatment of leaf tobacco in order to extract undesirable substancestherefrom. These undesirable substances may be either dark coloredmaterials or light colored materials but, in all circumstances, myimproved treatment process results in lightening oi the color of thetobacco'leaf so-that the resulting product is more valuable andattractive as a cigar wrapper.

In the manufacture of cigars it has been usual to employ Havana tobaccoleaves as wrappers for the more expensive grades. Tobaccos similar toHavana tobacco,-such as those grown in Connecticut and Florida, are alsofrequently 25 used for wrapping cigars, especially those of moreexpensive grade. Unfortunately, from about one-third to perhaps one-halfof the tobacco.

leaves grown in Connecticut and Florida or, more properly, those knownin the trade as Connecticut and Florida tobaccos, are toodark in colorto permit of their use in the manufacture of cigars.

The leaves of Sumatran tobacco have also been utilized to some extent ascigar wrappers but thus far it hasnot been possible to utilize therelatively cheaper tobaccos such as those grown in the States ofKentucky, North Carolina and Virginia for cigar wrapping purposes. Thesegrades and, in fact, all tobaccos except those known as Havana andSumatran tobaccos and to some extent the Connecticut and Floridatobaccos, have generally contained undesirable constituents and are toodark in color to permit extensive use or the leaves as wrappers in themanufacture of cigars. The trade has been obliged to utilize the moreexpensive tobacco leaves to enclose the filling tobacco oi cigars.

This has necessarily resulted in increased cost.-

It is one of the. objects of this invention to develop a process fortreating tobacco leaves intended for cigar wrappers so as to render themmorasatisiactory for use in the cigar manufacturing industry. While myprocess is especially valuable for treating tobacco leaves of therelatively cheaper tobaccos so as to permit of their utilization ascigar wrappers, the method may as objectionable.

Although most useful in connection with the treatment of less expensivetobaccos, the complete aim and object of this invention involves theimprovement of all lea-l tobaccos intended I for use as cigar wrappersby the development of a process, more particularly an extractionprocess, by which the color and shade of those tobacco leaves may besubstantially improved. It is another object-oi this invention to carryout this extraction process in such a manner that tendering of thetobacco leaf will be avoided. Very frequently, especially in the tobaccotreatment processes now known to the art, the to bacco led! at theconclusion of the process is so weakened that it readily crumbles uponbeing touched. Qbviously, a leaf having these characteristics hasabsolutely no value as a cigar wrapper. In the trade, this condition ofthe leal is termed "tender, and any process by which this condition isobtained is characterized as one which "tenders" the leaf.

The foregoing objects oi this invention, in volving the improvement ofthe characteristics of tobacco leaves intended for use as cigar wrappersby a process involving extraction, are to be accomplished with theadditional objective in view of securing this improvement in qualitywithout injuring or destroying those properties which permit of theutilization of those leaves in, the making of cigars. While it may bei'rewill be clarified and explained by the ensuing disclosure which isthe preferred method known to me for improving the qualities of leaftobacco as stated in the foregoing aims.

I have found that it is essential to subject the tobacco leaves to beimproved to a two-stage process, the first stage involving the use of awarm aqueous solution containing an agent which permits readypenetration of the surface of the tobacco leaves by the aqueoussolution. At the conclusion of this first stage treatment, which isessentially a surface treatment of the tobacco leaf, the washed leaf isno longer rough and uneven to the touch but presents avelvety feel. Thesecond stage in my improved two-stage process involves the use of anextraction bath wherein dark-colored and other objectionable principlesin the tobacco are extracted. Between the two operations, the first ofwhich may be termed a steeping or scrubbing operation while the secondis an extraction operation, the tobacco leaves may-be washed and/ordried. Drying may be carried out either by centrifugation, or bypermitting the tobacco to stand until its aqueous content has beenreduced. Usually, at the conclusion of the extraction process, theburning properties of the tobacco have been reluced to such an extent bythe extraction that the tobacco cannot be utilized as a cigar wrappingmaterial without restoration of these burning properties. Accordingly myprocess also involves the restoration, when necessary, of the mark name"DuponoP.

manuiactured and sold by the E. I. du Pont de Nem'ours 8: Company, Inc.,is a sulfated higher burning properties to the tobacco, either byincluding an agent serving to restore the burning properties in theextraction bath or by giving the tobacco a separate treatment with thisagent serving to improve burning qualities.

In order that the extraction process carried out in the second stage ofmy improvement process may be successful, I have found it essential thatthe first step, that of treating the tobacco leaves with warm aqueousliquor, be included in my complete tobacco treating process. In orderthat satisfactory extraction of both light and dark coloredobjectionableingredients may be secured it is essential that theextraction bath of the second step be utilized. Thus, neither step iseffective when utilized alone, but when both steps are employedconjointly the leaf improvement characteristic of my novel tobaccotreatment process is secured.

In the steeping or scrubbing step I have found it desirable to employwarm water, the temperature ranging from about F. to the boiling point.Preferably a temperature within the range' to 212 F. is employed. Duringthis step it is essential to include in the aqueous bath an agent whichwill permit the warm water readily to penetrate the surface of thetobacco leaves, thereby removing those waxy and other surface impuritieswhich render the tobacco leaf harsh and rough to the touch. As the agentto permit ready penetration of the surface of the tobacco leavesby thewarm aqueous solution I prefer to use a product such as that sold underthe trade- This product, which is alcohoi.sold generally for use inbleaching and dyeing baths wherever an effective wetting agent are usedin connection with these grades: ME WA Flakes"i' WAPaste; PW"; LS Paste;

and LS Flakes. The first four products are made by the sulfation oflorol, or alcohols obtained by reduction of coconut oil. The last twoproducts are made by the sulfation of ocenol, or alcohols obtainedby'reduction of sperm oil. Although other sulfated products, such asthose prepared as described in Schweitzer Patent 1,974,436 may also beused as agents permitting ready penetration of the surface of thetobacco by the warm water, I prefer to utilize Duponol as abovedescribed.

It may be stated at the outset that tobacco leaves are extremelysensitive to variations in alkalinity or acidity. If subjected to toohigh a degree of alkalinity they will become tender, readily crumblingor flaking when subjected to subsequent handling. Obviously tobaccoleaves which crumble or flake are worthless as cigar wrappers. On theother hand, in order that the extraction of undesirable and deleteriousconstituents may be carried out, it is essential to employ treatmentbaths which are alkaline in reaction. The problem in both stages of myprocduring the second stage of my process, that.

wherein an alkaline extraction bath is utilized, it is necessary thatthe pH be carefully regu lated within the range of pH values 8 to 11,preferably within the pH range 9 to 10. It may be stated as a generalconclusion that I have found it to be necessary when treating thetobacco with alkaline baths to maintain the pH at all times within thisrange in order that the resulting tobacco leaf may not be so impaired inquality as to render it worthless in the cigar wrapping industry.

It may also be stated that it has previously been suggested to treattobaccos with warm water and then to immerse the tobacco in an alkalinebleaching bath of hydrogen peroxide, which bath contains ammonia.However, the results secured by this process, which was a bleachingprocessas distinguished from an extraction process, have not beensatisfactory. The primaryreason for lack of commercial success was thefact that the preliminary hot water treatment did not cooperate with thesubsequent bleaching treatment in such a way as to insure a satisfactoryproduct. Another important reason for the failure of this process tomake any impression in the cigar wrapping industry was the fact that noattempt was made in the known process to control the alkali content orthe pH of the hyrogen peroxide solution utilized for bleaching duringthe bleaching phase. Merely utilizing a bath of hydrogen peroxidecontaining ammonia resulted in objectionable tendering of the tobacco,thereby securing a product which was practically valueless from thecommercial standpoint. This tendering must necessarily result from theuse of any bath of this character unless the quantity of ammonia orother alkali present is definitely restricted so that the pH fallswithin the range previously specified. When the pH is maintained withinthe range 8 to 11, preferably 9 to- 10, T have found the to is r that,surprisingly enough, the tobacco is not bleached, the bath of hydrogenperoxide 'containing ammonia acting as an extraction agent, extractingboth light and dark colored impurities from the tobacco. At theconclusion of my extraction step the extraction solution is extremelydark in color, a condition which would never obtain if the bath weresolely a bleaching bath as in the methods previously suggested in thisart. The novel characteristics of my process may he s 145th by statingthat the first stage operation so cooperates with the second as topermit ready extraction of undesirable principles from the tobacco, inthe second stage, without undue tendering or injury to the tobacco leaf.Another and important distinction between my process and thosepreviously suggested in the art is that I employ an extraction bathduring the second stage and not a bleaching'operation.

The first or steeping stage of my process employing the use of a warmaqueous solution, one

usually having a. temperature within the range- 160 to 212 F. andcontaining "Duponol" dissolved therein, has been previously referred to.This particular wetting agent has but little efiect on the pH of thesolution. As control of the pH is at all times important, the advantagesoi Duponol are apparent. During the actual extraction step the pH mustbe within the range to 11 and preferably within the range 9 to 10, butduring the preliminary treatment a pH not diifering substantially fromthat of neutrality is desirable. Since Duponol" gives such a solutionthis agent is to be regarded as a preferred ingredient in the steepingor scrubbing bath.

The ount of Duponolf present in this bath may vary from 0.01 to 1%, thisamount being by weight, based upon the amount .or liquid in the bath. 1have found that most satisfactory steeping baths are obtained whenDuponol in amounts ranging from 0.04 to 0.06% is added to warm water,the temperature 01' the water in all cases being above 100 F. andpreferably within the range 160 to 212 F. The tobacco is steeped in thisbath for a period usually ranging'i'rom 5 to 20 minutes although, insome cases, especially large scale commercial operations, it isneccssary to steep the tobacco for periods up to one hour or evenlonger. In addition to merely steepg the tobacco, some positivescrubbing action. may advantageouslybe maintained. This may beaccomplished by agitating the bath, either by hand, or by some positivemechanical means. In some cases scient agitation may be secured merelyby meg the tobacco by hand around lnthe warm aqueous bath. While I donot do sireto be limited to any exact ratio, or amount oi? tobacco treatto amount of steeping solu tion, it may be said that I have ordinarilyuti vd 60 gallons of solution to treat 60 "hands of tobacco. Since theweight of tobacco in a hand may vary somewhat, some tobaccos such asCoecticut tobacco weighing less per hand, a greater number of hands maysometimes be treated in the specified 60 gallons of solution. 5.: 5ratio of steeping solution to tobacco treated is to be regarded purelyas illustrative as, obvl= ously, as long as thorough wetting is secured,it is possible to employ almost any ratio of warm water to tobacco.

after the requisite immersion period, a period usually not exceeg 20minutes but in some cases, especially where relatively large amounts oftobacco are handled, extending up to one hour, is removed irom the warmbath and treatment in a centrifugal drying machine.

either washed with warm water or subjected to It has been found thatafter washing with hot water and being permitted to dry by standing fora short period of time, the tobacco will retain about 2 pounds of waterper pound of tobacco. After centrifugation, on the other hand, the watercontent of the tobacco will have been reduced to approximately 1 poundof water per pound of tobacco. Either method of treatment of the tobaccoafter it has been removed from the treating and scrubbing bath may becarried out. When removed from the. steeping bath it will be noticedthat this bath is exceedingly dark in longer, in a bathcontaining'hydrogen peroxide and water. The quantity of ammoniapresentin.

this extraction bath must be carefully regulated so that the pH shallfall within the range 8 to 11, preferably within the pH rangev 9 to 10.This be sufficient so that the ammonia (NHa) content of the extractionbath ranges from about 0.002% to about 1%, preferably from about 0.006%to about 0.25%. These percentages are approximate NHa percentages whichwill yield pH' values within the range previously specified. When theNI-is addition is made by adding a solution of ammonium hydroxide, theammonia content of that solution must be taken into account, unless, asis probably the preferable procedure, the correct amount of. commercialammonium hydroxide solution to be added to any given bathis determinedby pH observation.

The quantity of hydrogen peroxide present in my extraction bath may varyfrom 0.03% to 11.00%. (approximately 0.1 volume to 3.3 volumes). As inthe case of the ammonia concentration these percentages are actualcomputed percentages based on the weight of active agents added to thebath. When utilizing a solution of hydrogen peroxide, such as thecommercial 100 volume Albone containing a hydrogen peroxide content of Iapproximately 28% by weight, the hydrogen peroxide percentage of thesource of hydrogen peroxide must be taken into consideration indetermining the amount of this commercial solution to add to anyextraction bath. I have found that a hydrogen peroxide concentrationranging from 0.85 to 0.90% yields most satisiactory results when theextraction bath is maintained at a temperature within the range 100 to175 F. My preferred extraction bath-is maintained at a temperaturewithin the range 120 to 130 F. but, in some cases, the temperature maybe as low as 100 F. and in other cases the temperature may go up to 200f. or even slightly higher, for example to the boiling point. However,it is usually unwise to employ a temperature in excess of about 175 F.for the extraction bath.

The tobacco is preferably immersed in the Warm alkaline hydrogenperoxide solution, forming the extraction bath, for a'period of ten tothirty minutes. In some cases immersion perithis of an hour or evenlonger may be glyph- 30 means that the amount of ammonia added musttageously utilized. When treating tobacco which is relatively light incolor and from which but few objectionable principles are to be"extracted, immersion periods of less than ten minutes may suffice.

The action taking place in the second stage of my process is essentiallyan extraction process. As in the first stage of my process, (which alsoacts to extract undesirable principles from the tobacco), the treatmentsolution becomes very dark in color and this dark color continues for avery considerable period of time after the tobacco has been removed fromthe bath. Finally, some hours after removal of the tobacco from thebath, suflicient bleaching action takes place in the bath as a result ofthe hydrogen peroxide present therein so that the solution be comesappreciably lightened in color. After standing for periods ;of threehours or more the solution, which is extremely dark in color after theremoval of the tobacco therefrom, changes in color to a very light greenand is characterized by remarkable clarity.. This latter effect is moreproperly a bleaching effect, the peroxide actin .to bleach thedark-colored extracted impurities present in the bath, but during theactual treatment of the tobacco in the solution containing hydrogenperoxide and ammonia no substantial bleaching action occurs and thetobacco is improved almost solely as the result of the extraction ofobjectionable principles therefrom.

It has been observed that if the extraction bath is maintained atatemperature much over 175 F. tendering of the leaves, as well asvigorous decomposition of the hydrogen peroxide present in theextraction bath, will occur. Surprisingly enough, the extraction of bothlight and dark colored impurities appears to be less at this temperaturethan at lower temperatures. Accordingly a temperature within the range:129 to 130 F. is to be regarded as preferred. The decomposition ofhydrogen peroxide observed to some extent with the extraction bath atthis temperature appears to be primarily the result of the elevatedtemperature, as well as due to the presence of an alkali in the bath,and it is attributable in but very small measure to any actual oxidationof impurities present in or on the tobacco. The greater portion of thedecomposition of hydrogen peroxide does not occur to any appreciableextent during the period in which the tobacco is immersed in theextraction solution in any case, but takes place after the removal ofthetobacco from the solution. The dark-colored principles extracted fromthe tobacco and present in the extraction bath are bleached by theaction of the hydrogen peroxide after removal of the tobacco from thebath, but during the period wherein the tobacco is immersed in the baththe bleaching activity of the hydrogen peroxide seems be distinctlysubordinated to its hydrolytic or other action which renders the bathextremely effective as an extraction medium.

After removal of the tobacco from the extraction bath it may besubjected to centrifugal drying and then hung up to dry in any wellknown type of drier. The centrifugation is not essential, as the tobaccoleaves may be merely permitted to drain excess solution back into thebleaching bath and then hung up to dry. The resulting product will befound to be of velvety texture, without any appreciable tendency toflake or crumble, and of a very satisfactory light color. Theobjectionable principles have been removed and the tobacco seems to beactually milder in taste and flavor. Curiously enough, no appreciableamount of tendering of the tobacco leaves occurs and in this respectmy-process is a striking improvement" over older processes wherein themajor portion of the tobacco leaves treated usually become so tenderduring the treatment as to prevent their use as tobacco wrappers.

Since the burning qualities of the tobacco are usually completelydestroyed or at least seriously impaired during the extractiontreatment, is

usually necessary to restore the burning properties by treating thetobacco with any treatment agent now well known in the art to accomplishthis purpose. After removal from the extraction bath, and beforecentrifugation or drying, the tobacco may be immersed in a solution ofpotassium acetate which may contain, for example, approximately 12.5pounds of the salt per 100 gallons of solution. This approximates about15 grams of potassium acetate per liter of solution. Or, if desired, thepotassium acetate may be placed directly in the extraction bath so thatafter removal from the extraction bath the tobacco is ready forimmediate drying. While potassium acetate in the amount specified hasbeen found to give very satisfactory results in restoring burningproperties to the tobacco, any other agents well known in the art, ornow used for this purpose in the tobacco industry may be utilized.

It will be obvious to those skilled in the art that various changes maybe made in my process without departing from the spirit of theinvention. Therefore, I do not desire to be restricted to the precisedetails of my process hereinbefore described as illustrative. The scopeof my invention is to be construed in accordance with the appendedclaims and the prior art. Wherever in these claims Duponol is referredto, it is my intention to signify the product sold under that trade-markname previously identified. 1

I claim:

1. A process of improving tobacco which comprises steeping said tobaccoin a bath of warm water hating a temperature in excess of F.

and containing Duponol in amounts up to 1% and, thereafter, immersingsaid tobacco in an extraction bath having a pH within the range 8 to 11and comprising hydrogen peroxide in amounts ranging from 0.03% to 1% andam-" 'monia in amounts ranging from 0.002% to about 1%, all saidpercentages being by weight based on the amount of liquid in the bath.

2. A process for improving tobacco which comthat it possesses a pH valuewithin the range 8' to 11, all percentages specified being by weight,based on the weight .of liquid in'the respective baths.

3. A process for improving tobacco which com:

prises the steps of steeping said tobacco. ina warm aqueousliquid havinga temperature--be= tween 160-F, and its boiling point which con tainsDuponol in amounts ranging from 0.04 to 0.06% by weight, based on theweight of said aqueous liquid, and, thereafter; immersing said tobaccoin an extraction bath having a pH within the range 8 to 11 andcontaining hydrogen peroxide in amounts ranging from 0.03 to 1.00%, byweight, based on the weight of said extraction bath.

4. A process for improving tobacco which comprises steeping said tobaccoin a bath of warm water having a temperature within the range 160-212"F. in the presence of an agent permitting ready penetration of saidtobacco surfaces by said water, said agent being present in at least0.01% by weight based on the weight of in an extraction bath containinghydrogen per- 10 oxide and having a pH within the range 8 to 11.

ALFRED T. HAWKINSON.

